Cleanup panzoom implementation

src/lib/panzoom/util.ts

@@ -0,0 +1,23 @@
+import panzoom from 'panzoom';
+import type { PanZoom } from 'panzoom';
+import { writable } from 'svelte/store';
+
+export const pz = writable<PanZoom | undefined>(undefined);
+
+export function initPanzoom(node: HTMLElement) {
+  pz.set(
+    panzoom(node, {
+      bounds: false,
+      maxZoom: 10,
+      minZoom: 0.1,
+      zoomDoubleClickSpeed: 1,
+      enableTextSelection: true,
+      beforeMouseDown: (e) => {
+        const nodeName = (e.target as HTMLElement).nodeName;
+        return nodeName === 'P';
+      },
+      beforeWheel: (e) => e.altKey,
+      onTouch: (e) => e.touches.length > 1
+    })
+  );
+}